I've got a random orbital sander and it's done well on the stairs but I thought a sheet sander would be better for slightly big areas of floorboards so you can go with the grain and you're less likely to get the circular scratches you can get with an orbital.
I’ve got a mirka and use it for so much, but as mentioned you seems to get issues when your too heavy. I try and let the machine do most of the work and keep the pads fresh too.
I've got a random orbital sander and it's done well on the stairs but I thought a sheet sander would be better for slightly big areas of floorboards so you can go with the grain and you're less likely to get the circular scratches you can get with an orbital.